IET Labs has designed the SCA-1nF-8588A to calibrate the Fluke 8588A 1 nF capacitance range as discussed in the Verifying the capacitance function of the 8588A Reference Multimeter Applications Page.
The 1 nF range in the Fluke 8588A is the only range that does not use a resistance range and can be checked/calibrated with the SCA-1nF-8588A. The other capacitance ranges can be monitored by observing the change in the appropriate resistance range.